Tool mark striations in pig skin produced by stabs from a serrated blade

Stab wounds produced by serrated blades are generally indistinguishable from stab wounds produced by non-serrated blades, except when visible tool mark striations are left on severed cartilage. Using a pig-skin experimental model, we explored the possibility that similar striations may be left in skin. Stabs into pig skin were made using a straight spine coarsely serrated blade (121), a drop point finely serrated blade (20), a clip point irregular coarsely serrated blade (20), a drop point coarsely serrated blade (15), and as controls 2 non-serrated blades (40). Tool mark striations could be seen on the skin wall of the stab canal in all stabs made using serrated blades but in none with non-serrated blades.The striation pattern, reflecting the class characteristics of the serrated blade, was the same as that described in cartilage but less well defined. Fixation of the specimen with Carnoy's solution best preserved visible striations, and fixation with formaldehyde after staining with 5% Neutral Red was also satisfactory. Casting with vinyl polysiloxane dental impression material greatly facilitated photo-documentation. Applying the technique to homicidal stabbings may help identify stab wounds produced with serrated blades.     

Defined contusion marks caused by the knife handle]

If in inflicting a stab wound the knife is vigorously pushed in up to the end of the blade, this does not only cause cutting of the tissue, but also a blunt traumatization. The resulting abrasions can correspond with the respective construction parts (handle, handguard, devices for fixing the open blade) as to position, shape and size, thus allowing conclusions as to the shape of the instrument used. Incomplete, one-sided marks of the handle suggest an oblique-angled stab. The presence of a contusion mark shows that the blade penetrated completely, which makes it easier to draw conclusions as to the length of the blade from the depth of penetration. The reconstruction possibilities are demonstrated on the basis of three autopsies (homicide cases with different types of knives).     

The Cane Sword

This report provides an overview of the injuries caused by a unique blade‐type weapon known as a cane sword. The cane sword usually consists of a blade that is stored in a cylindrical “cane” that can be released at the handle to reveal the hidden blade within. The victim of the case was found to have a stab wound in the left mid‐back that caused perforation of both the lower and upper lobes of the left lung, resulting in a left hemothorax. Upon autopsy, it was concluded that the patient died from injuries caused by the stab wound to the back. Given the shape of the wound and the fact that the weapon itself was found at the site of the homicide, the weapon that caused the injury was believed to be a cane sword. This case will inform forensic pathologists, law‐enforcement officers, emergency medical personnel, and physicians about rare weapon, the cane sword.     

Striation patterns in serrated blade stabs to cartilage

Stab wounds were made in porcine cartilage with 13 serrated knives, amongst which 4 were drop-point and 9 straight-spine; 9 coarsely serrated, 3 finely serrated and 1 with mixed pattern serrations. The walls of the stab tracks were cast with dental impression material, and the casts photographed together with the knife blades for comparison. All 13 serrated blades produced an "irregularly regular" pattern of striations on cartilage in all stabbings. Unusual and distinctive blade serration patterns produced equally distinctive wound striation patterns. A reference collection of striation patterns and corresponding blades might prove useful for striation pattern analysis. Drop-point blades produced similar striations to straight-spine blades except that the striations were not parallel but rather fan-shaped, converging towards the wound exit. The fan-shaped striation pattern characteristic of drop-point blades is explained by the initial lateral movement of the blade through the cartilage imposed by the presence of the drop point shape. It appears that the greater the overall angle of the drop point, the shorter the blade length over which the drop point occurs, and the closer the first serration is to the knife tip, the more obvious is the fan-shaped pattern. We anticipate that micro-irregularities producing individualising characteristics in non-serrated drop point blades, provided they were located at the tip opposite the drop point, should also show a fan-shaped pattern indicative of a drop point blade. The examination of the walls of stab wounds to cartilage represents an under-utilised source of forensic information to assist in knife identification.     

Microscopic Analysis of Sharp Force Trauma in Bone and Cartilage: A Validation Study,,

Sharp force trauma research lacks agreement on reported error rates for correctly identifying toolmark characteristics on bone and cartilage. This study provides error rates for determining blade class (serrated, partially serrated, nonserrated) and type of edge bevel (left, right, even). Three analysts examined cuts to a wax medium, cartilage, and bone using two types of microscopes. Additionally, the observers examined impressions taken from the wax medium and the cartilage. Overall, a total of 504 observations were performed. Serrated blades were distinguishable from nonserrated blades due to their patterned striations. Some difficulties were encountered in distinguishing serrated and partially serrated blades; however, when these groups were considered together as one classification type (serrated), classification accuracy improved from 79% to 96%. Classification accuracy for edge bevel was 65%. Error rates were similar when comparing direct observation of the cut marks versus indirect observation (impressions). Additionally, the type of microscope used did not affect error rates.     

Can a machine be used to replicate the biomechanics of human stabbing performance?

A human performance trial was conducted where the stabbing actions of 40 participants were investigated. A range of factors were assessed such as the action used when the blade shape and familiarity of the knife changed. A qualitative evaluation of these factors was presented in an earlier paper to precede the analysis of quantitative kinematic data in this paper. The data from participants was then compared to that obtained from a stabbing machine.A motion analysis system was used to measure parameters such as the joint angular displacement and absolute linear velocity at impact. Motion data was collected using a 12-camera Vicon MX motion analysis system. Results indicated that the mean absolute linear velocity of overarm stabbing actions was consistently higher than the underarm actions.Forensic textile damage examinations often involve testing of edged weapons by manually performing stabbing actions. An underlying fundamental limitation of manual simulation experiments is the natural variation inherent in human performance. Sufficient control measures can be implemented to successfully use manual simulation experiments in forensic testing and therefore this is the accepted practice. However, performance can be improved using a stabbing machine. A custom-built instrumental stabbing device has been shown to operate within the same parameters of the human participants and is therefore suitable for use in casework.     

Correlation between saw blade width and kerf width

Most studies of saw marks have focused on morphological characteristics and their utility in identifying saws suspected to have been utilized in cases of criminal dismemberment. The present study examined the extent to which metric analysis may be used to correlate saw blade measurements with minimum kerf widths (MKWs). A sample of 56 partially defleshed white‐tailed deer (Odocoileus virginianus) long bones was utilized as proxy for human remains. The long bones were cut using a variety of commercially available saws, including 11 manual‐powered and 5 mechanical‐powered saws. A total of 496 false start kerfs (FSKs) were created. Two experiments were performed, with the first test examining the MKWs of FSKs produced on specimens that were restrained using a bench vise, while the second test analyzed the MKWs of FSKs produced on minimally restrained specimens. Statistical analysis using Hierarchical Linear Modeling (HLM) indicated a positive relationship between saw blade width (mm) and MKW, with blade width (p < 0.001) and the overall difference between the mechanical‐ and manual‐powered saws (p = 0.029) tested, reaching statistical significance. A comparison of MKWs produced using manual‐powered saws on restrained and minimally restrained bones suggests that restraint condition (p = 0.009) has a statistically significant effect. In comparisons of MKWs to blade widths, the average ratio for mechanical‐powered saws is 18.7% greater than the average ratio for manual‐powered saws. While the mode of the ratios was 1.42, thus supporting the general rule that MKW does not exceed 1.5 times blade width, multiple individual ratios did surpass 1.5.     

Puncture wounds caused by glass mistaken for with stab wounds with a knife

Three cases are presented where fatal puncture wounds caused by broken glass were very similar to stab wounds inflicted by a knife with a single-edged blade. Thus, all three cases caused a murder investigation to be initiated. It could only be determined that these wounds had been caused by glass after a detailed forensic autopsy. In two of the three cases, the only evidence for this was the identification of glass fragments in the wounds. The importance of X-ray examinations is underlined because modern glass in common use is radiopaque. Glass fragments lodged in the wounds can reduce the loss of blood and thus, prolong the capacity to act despite severe injuries.     

人与狗、猪、牛、羊长骨哈氏系统图像分析的比较

目的探讨人与狗、猪、牛、羊长骨的哈氏系统的形态特点、图像分析特点及其鉴别要点。方法制作人与狗、猪、牛、羊长骨中段横切磨片35张,光镜下观察比较哈氏系统,并在研究型显微镜下进行图像分析。结果人骨无丛状骨和骨单位带;人与狗、猪、牛、羊骨的哈氏系统在形状、大小、分布位置、均匀程度等方面存在明显差异;人骨哈佛骨板层数最多,哈氏系统直径最大;中央管直径和面积百分比的图像分析结果显示人与动物骨的差异均有显著意义。结论(1)丛状骨、骨单位带在种属鉴定中可作为人骨的排除指标;(2)人骨与狗、猪、牛、羊骨在哈氏系统结构方面有明显区别;(3)利用图像分析进行种属鉴定,中央管面积百分比是区别人骨与动物骨的重要参考指标。     

Identification of incinerated root canal filling materials after exposure to high heat incineration

With the increase in global terrorism there is a higher probability of having to identify victims of incineration events secondary to incendiary explosive devices. The victims of incineration events challenge forensic odontologists when coronal restorations are no longer present to compile postmortem data. With 40 million root canals being completed annually in the United States, a very large pool of antemortem data is available to the forensic odontologist to make positive identifications. When complete and thorough dental records exist, individuals that have undergone surgical and nonsurgical root canal therapy may have materials present in the canal that may aid in identification. This study provides elemental fingerprints of root canal obturation materials to be utilized as a forensic identification aid. This study used scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) to assess the elemental composition of materials before and after high temperature incineration. Sixteen endodontic materials were analyzed pre-incineration and placed in extracted teeth. The filled teeth were subjected to incineration at 900 degrees C for 30 min to simulate incineration events or cremation. Incinerated materials were radiographed and re-analyzed to determine if they retained their original elemental composition. Endodontic sealers, gutta percha, root-end filling materials, silver points, and separated files were distinguishable in the canal and traceable after incineration. The authors present a fingerprint of the endodontic obturation materials that are capable of withstanding high heat incineration to be used as an aid for postmortem identification. This work represents the initial stage of database generation for root canal filling materials for use as an aid in forensic identification.     

Identify the injury implements by SEM/EDX and ICP-AES

The forensic investigator is frequently confronted with the discrimination and deduction of injury implements, which is one of the most important physical testimonies in courts. The usual method used in actual cases is from points of morphology. In the forensic discrimination of injury implements, such as metal implements, the analysis and comparison of elements are expected to provide excellent results, and simultaneous multi-elemental analysis is required to analyze various kinds of elements. This study was designed to establish discrimination and deduction of metal injury implements by scanning electron microscope/energy disperse X-ray microanalyzer (SEM/EDX) and inductively coupled plasma atomic emission spectrometry (ICP-AES). Examined metal particles in five wounds made on the skin of domestic pigs, respectively, using Cu-Zn or Cr-Ni coated and carbon steel kitchen implements by EDX. For carbon steel kitchen implements, analyzed five samples from the back and blade separately in the contents and varieties of elements by ICP-AES. In the wounds by the coated implements, the special particles only containing Cu, Zn or Cr, Ni were found. In the wounds by carbon steel kitchen implements, the particles containing Fe, Cr, Si or Fe, Mn, Si were found. The differences of contents of elements between the back and blade was no significant except No. 5 for carbon steel kitchen implements, and the significant differences of elements exited in Cr, Mn, Si, Cu, Mo among the stainless kitchen knives, Mn, Si among the other kitchen implements and for the blade of No. 5 knife, relative standard deviations (R.S.D.s) were significantly different in Mn, Si, Mo, Ti, S, P, Ni. Using EDX to examine the particles in wounds can deduce the categories of metal injury implements, and we can still deduce the different implements in the same category by ICP-AES.     

Estimation of age from the femur of Japanese cadavers

The purpose of this study is to estimate the age of cadavers by histomorphometry of the femur. Seventy-two Japanese males ranged from 43 days to 92 years old and 26 females ranged from 2 to 88 years old were used. The thickness of sections was adjusted at 50 to 70 microns by grinding with sand paper. The sections were not decalcificated. They were stained with Villanueva's bone staining powder and with thionin dye. Microradiographs of the sections were obtained by the soft X-ray apparatus. The area, maximum and minimum diameter, and perimeter of the perfect osteon and Haversian canal were measured. In addition, the type II osteon number, osteon fragment number, and area of triangle were also determined. All these parameters were examined by an image analyzer. The parameters of the osteon showed high correlation coefficient with age (magnitude of r > 0.77), while those of the Haversian canal were low (magnitude of r < 0.11). All parameters were subjected to multiple regression analysis for producing a multiple regression equation of age estimation. For the stepwise selecting method, the perimeter of osteon, maximum length of the Haversian canal and osteon fragment number were selected for the equation. Their multiple r2 and standard error of estimation were 0.8874 and 6.39, respectively. For the forward selection method, in addition to the above items, three parameters, the maximum length of Haversian canal, triangle area, osteon fragment number were selected. Their multiple r2 and standard error of estimation were 0.9484 and 4.884, respectively. Bone staining was useful to clarify the demarcation between osteon and fragment, leading to an increase in the accuracy of age estimation. However, the entire range from birth to 90 years was difficult to cover for precise age estimation.     

Chemical trace XRF analysis to detect sharp force trauma in fresh and burned bone

Forensic anthropologists may not always be able to differentiate heat-induced fractures from fractures with other aetiologies, namely sharp force traumas, with clear nefarious impact on medico-legal conclusions. The objective of this study was to experimentally investigate if blade chemical traces are transferred to defleshed bone tissue and if they remain there after a burning event. This was accomplished by prompting sharp force traumas in 20 macerated fresh pig ribs with five different instruments, namely a stainless steel knife, an artisanal knife and a ceramic kitchen knife, a small axe and a large axe. Another pig rib was used as control, not being subjected to any trauma. All instruments were probed by X-ray fluorescence (XRF) to establish the composition of each blade. Bone samples, both pre-burned and post-burned (at 500 °C, 700 °C, 900 °C and 1100 °C), were then probed by XRF. All sharp force instruments left detectable chemical traces on pre-burned bone, although not in all samples. Furthermore, traces were still detected after experimental burning in most cases. Potentially, XRF can provide relevant information about the aetiology of fractures in burned and unburned bones, although the effect of soft tissues and diagenesis must still be investigated.     

Virtual casting of stab wounds in cartilage using micro-computed tomography

In homicidal stabbings using a serrated knife, stab wounds involving costal cartilage leave striations on the cut surface of the cartilage from the serration points on the blade edge. Class characteristics of the serrated blade can be determined from the striation marks, and individualizing characteristics may be seen also. The traditional method for recording the striation marks involves the pernickety technique of casting with dental impression material. We assessed the potential utility of micro-computed tomography scanning of the stab track as a technique for nondestructive recording of striation patterns and virtual casting of them. Stab tracks in porcine cartilage, produced with a coarsely serrated blade, were scanned with a bench-top micro-computed tomography scanner. The typical irregularly regular striation pattern could be demonstrated, and the images manipulated, using proprietary software to produce a virtual cast. Whether the technology will have sufficient resolution to image not only class characteristic tool marks but also the much finer individualizing tool marks remains to be evaluated, but the technology shows considerable promise.     

Radiograms of the paranasal sinuses as a principle of identifying catastrophe victims and unknown skeletons

The paper is devoted to the identification on the base of X-ray of frontal sinuses. These sinuses, developed in puberty doesn't change its shape during aging. Differentiation of the size and shape of sinuses is remarkable and probably is one of the individual features of the man. The system of classification of sinuses is proposed, basing on the area size, shape and symmetry. In the current everyday practice all X-ray radiograms are destroyed after five years of storage in Poland. For identification purpose all radiograms of sinuses and A-P punctures of skull should be stored in radiology departments, and arranged according to proposed classification system. The case is presented, in which the pictures of skull were the base of successful identification of skeleton.     

On a knife edge: A preliminary investigation of clothing damage using rounded-tip knives

Bladed weapons are frequently encountered in violent crime offences including street based and armed robberies, murder, sexual assaults and terrorism. A study was conducted involving four frequently encountered clothing fabrics: t-shirt (knitted cotton), denim jeans (twill woven cotton), long sleeved top (knitted synthetic blend), and skirt (non-woven faux leather) and five knives to investigate any damage resulting from a downward stabbing motion, with 300 stabs in total. Any resultant penetrating severance damage was then photographed, measured and analysed. Statistical analysis revealed significant differences between the stab hole size and shape, as a consequence of the design of a bladed weapon (in particular, the tip shape) that caused it. There is a notable correlation between the Assure knife (rounded tip) and no resulting severance damage, as the fabric surfaces were not breached with this knife. This suggests a clear alternative to pointed tip knife blades. These findings will be of interest to investigators of knife crime offences, crime-reduction units, knife manufacturers and practitioners, who share the goal of identifying a safer alternative to conventional knife blade design.     

Diagnostic postmortem angiography of fatal splenic artery haemorrhage

The site of fatal haemorrhage from the splenic artery, caused in one case by a ruptured aneurysm and in another case by an intracystic haemorrhage of a postoperative pancreatic pseudocyst, was revealed by postmortem angiography. Radiopaque silicone rubber vulcanizing at room temperature was used as contrast medium. In the latter case, the dissection was seriously hampered by tight postoperative intestinal adhesions following four abdominal operations to control bleeding into the gastrointestinal tract. The results indicate the usefulness of postmortem angiography with contrast medium vulcanizing at room temperature for postmortem diagnosis of rare causes of gastrointestinal haemorrhage.     

Morphological and spectroscopic measurements of plastic bags for the purpose of discrimination

The discrimination of noncolored transparent polyethylene bags was studied by several nondestructive and semidestructive analytical methods. X-ray diffraction, infrared spectroscopy, and optical microscopy (differential interference contrast microscopy and phase contrast microscopy) were applied to polyethylene films. X-ray diffraction was used to distinguish variations in the crystalline phase, infrared spectroscopy was used to distinguish variations in the molecular components, and optical microscopy was used to distinguish the different surface morphologies. The results show that X-ray diffraction classifies the crystalline phase of the film depending on whether it is made from low-density polyethylene, linear low-density polyethylene, or high-density polyethylene; that infrared spectroscopy is useful to distinguish the molecular components and it is the most discriminating technique; and that optical microscopy discriminate films easily by their morphological differences.     

Reduction of postmortem angiography-induced tissue edema by using polyethylene glycol as a contrast agent dissolver

Postmortem investigation is increasingly supported by computed tomography (CT) and magnetic resonance imaging, in which postmortem minimal invasive angiography has become important. The newly introduced approach using an aqueous contrast agent solution provided excellent vessel visualization but was suspected to possibly cause tissue edema artifacts in histological investigations. The aim of this study was to investigate on a porcine heart model whether it is possible to influence the contrast agent distribution within the soft tissue by changing its viscosity by dissolving the contrast agent in polyethylene glycol (PEG) as a matrix medium. High-resolution CT scans after injection showed that viscosities above c. 15 mPa s (65% PEG) prevented a contrast agent distribution within the capillary bed of the left ventricular myocardium. Thereby, the precondition of edema artifacts could be reduced. Its minimal invasive application on human corpses needs to be further adapted as the flow resistance is expected to differ between different tissues.     

Suicidal Decapitation by Guillotine: Case Report and Review of the Literature

Abstract: Suicidal decapitation is seldom encountered in forensic medicine practice. This study reports the analysis of a suicide committed by a 31‐year‐old man with a self‐fabricated guillotine. The construction of the guillotine was very interesting and sophisticated. The guillotine‐like blade with additional weight was placed in a large metal frame. The movement of the blade was controlled by the frame rails. The steel blade was triggered by a tensioned rubber band after releasing the safety catch. The cause of death was immediate exsanguination after complete severance of the neck. The suicide motive was most likely emotional distress after the death of his father. In medico‐legal literature, there has been only one similar case of suicidal complete decapitation by a guillotine described.